A police review has taken nearly four years and come no closer to answering the question that has puzzled the country for nearly 44 years: who killed the Crewes? That was the first question asked of them, through the Herald in 2010, by their daughter Rochelle, just 18 months old when she was found in her cot five days after her parents where shot.
The second question was, should detectives have been prosecuted for fabricating evidence that led to the wrongful conviction of Arthur Allan Thomas? On that question, too, the review leaves us no wiser. It has found no evidence to challenge the view of the Solicitor General in 1981 that despite the findings of a royal commission there was insufficient proof to prosecute anyone for planting a cartridge case in the Crewes' garden.
But at least the report by Detective Superintendent Andrew Lovelock does not echo the outright denials of a previous generation of police that Detective Inspector Bruce Hutton and Detective Len Johnson might have planted evidence. That attitude was still evident as recently as last year in a eulogy to Hutton by the Deputy Commissioner, now Commissioner, of Police, Mike Bush. In that respect the Lovelock report represents some progress.
The review team concludes that the cartridge case "may" be fabricated evidence because it could not have contained the bullets that killed the Crewes, and says that "if" it was planted for that purpose a member of the police was responsible. The review considers that the royal commission's finding in 1980 ought to have prompted Police Commissioner Bob Walton to order a criminal investigation of Inspector Hutton and Detective Johnson, who had died in 1978.
It is confident that would have been the response today, if only because an Independent Police Conduct Authority could initiate an investigation. Yet the review stops short of recommending a criminal investigation of these matters now, because it has found no more evidence than was available when Solicitor General Paul Neazor decided against a prosecution in 1981.
In his review of the original murder inquiry in 1970, Mr Lovelock has found serious deficiencies, most of which cannot be repaired four decades later. The 1970 investigation did not corroborate the presence of every person at three community events in Pukekawa on the night of the murders. Sightings of vehicles at the Crewe farm in the days between the couple's estimated time of death and the day they were reported missing, were not thoroughly followed up.
The 1970 investigation did not take sufficient interest in a burglary of the Crewes' house and two suspicious fires at the farm in the years before their deaths. The crime scene was poorly secured and managed, and not for the first time, a review of the case is critical of the decision to dump exhibits at the Whitford tip in 1973.
The review believes the detectives' initial focus on Jeanette Crewe's father, Len Demler, "significantly and negatively impacted the investigation and led to a loss of objectivity". The review team found "no credible evidence" against Demler or a number of others said to be involved. When items from the Thomas farm became evidence, it says, insufficient investigation was made of others who had access to the rifle, axle and wire around the bodies.
Mr Thomas, the review reports, declined to be interviewed or participate in any formal discussion this time. Having been twice tried and convicted, then pardoned and compensated for serving nine years in prison, he surely had a right to be left alone.
The Lovelock report will take its place alongside trial transcripts, books, documentaries, the royal commission report and numerous lesser investigations, but the questions remain. They will tantalise the country for many years yet.